High energy costs have increased concern for the efficient heating, ventilating and air conditioning of buildings, particularly larger office and multi-residential structures. Such structures, especially office buildings, typically have a central heating, ventilation and air conditioning system, of course, exterior walls, and at least one story having a true ceiling, a suspended ceiling, and lighting fixtures occupying openings in the suspended ceiling. The true and suspended ceilings are vertically spaced thereby to form a plenum. A considerable amount of heat is generated by the lights during their operation. It has been proposed to collect this heat by means of ducts, but the transporting of this heat through ducts in itself consumes energy.
It is an object of the present invention to provide a much more effective means for regulating and making use of the heat generated by the lighting fixtures in operation.
Representative prior art U.S. patents (a copy of each of which was submitted with the parent application) are as follows, U.S. Pat. Nos.: 3,124,903 (Truhan); 3,366,165 (Beeler); 3,403,614 (Carnes); 3,626,837 (Pelosi); 3,693,530 (Larkfeldt); and 3,742,837 (Samuelsson). The present invention is, however, patentably distinct from the prior art.
The Beeler patent appears to be the most relevant of the foregoing patents. Beeler discloses an air conditioning system wherein separate systems are provided to compensate for the heat load passing through the walls of the structure, for the heat generated internally by the lights in the structure and for the heat and moisture produced by the people occupying the structure. Beeler states that in this manner, the system performs most efficiently since it is not necessary to provide fresh humidity-controlled air in the first two of these systems. A perimeter system controls the flow of heat through the walls and roof of the building, the light system controls the heating of the interior of the building and the interior system supplies properly treated air for contact with the people using the building. This system includes a ceiling plenum chamber 70 containing fluorescent tubes 75. It would appear that in this system heat radiates from the ceiling 77 forming the bottom of the plenum chamber 70 into the room 71. Ducts 86 provide conditioned air to the plenum 70 whereby the temperature in the plenum 70 can be regulated. A separate source of conditioned air is provided for the space between the outer walls of the building, inner and outer windows also being provided. Superficial similarities to the present invention appear in two respects. One is the controlling of the temperature in a lighting plenum to provide a controlled radiant heating ceiling. The other is the provision of separate systems for peripheral and core zones of the building. In the present invention, however, the controlled temperature plenum ceiling is for peripheral zones and only for peripheral zones of the building. Many other distinctions between the present invention and the disclosure of the Beeler patent will be apparent from the hereinbelow description of the present invention.
The other patents noted above are much less pertinent to the present invention. Truhan provides a controlled chamber particularly adapted for growing plants. As a whole, the system is very much different in construction, purpose and effect from the present invention. From just a simplistic point of view, it may be noted, for example, that the plenum 34 in Truhan is not completely closed but, rather, communicates with the "room space" thereinbelow through apertures in plates 28 and 30. A similar comment applies to the ceiling air plenum of the Carnes patent and, likewise, the Pelosi patent. The Larkfeldt patent is merely of very general interest since it simply relates to a ventilated fluorescent tube fixture in which heat is provided in the room by blowing air through the fixture. The Samuelsson patent is of this same general nature but more sophisticated, in that the lighting fixtures communicate with plenum spaces between double windows in order to help control heat transmission through the windows, but there is no essential relation to the present invention.